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destination overlay transparent

Posted: 2011-05-24T04:32:54-07:00
by dicko
Hi all,

In Paint Shop Pro you can add a layer, set its blend mode to Overlay and make the layer not 100% opaque.
Is something similar possible in IM?

I allready got a result using

Code: Select all

convert lightandshadow.png floor.png -compose Overlay -composite result.png
but I would like to make the destination 50% transparent.

Does anyone have an idea?
Thanks.

Re: destination overlay transparent

Posted: 2011-05-24T10:31:35-07:00
by fmw42
if you want the result.png image to be 50% transparent, then

convert lightandshadow.png floor.png -compose overlay -composite -alpha set -channel a -evaluate set 50% +channel result.png

But I be sure you have your two images in the right order

see http://www.imagemagick.org/Usage/compose/#overlay
see transparent canvas under http://www.imagemagick.org/Usage/canvas/#other

Re: destination overlay transparent

Posted: 2011-05-24T17:32:25-07:00
by anthony
That is the method to use. "composite" can't do multiple operations on images, so you will need to use convert.

NOTE however that Overlay composition is NOT the same as Over composition. Over being more typically what is wanted in 'blend/dissolve' image merging. Overlay is a lighting mode and typically not used with 'transparency blending'

This is true of either IM or in Photoshop!

I suggest you read IM examples, Composing Images.
http://www.imagemagick.org/Usage/compose/